The present invention relates generally to imaging systems and, more specifically, to an adjustable focus imaging device.
Imaging devices are used to produce machine-readable image data (image data) that is representative of an image of an object, e.g., a page of printed text. The process of generating image data is sometimes referred to as capturing or imaging an object. One type of imaging device is a photoelectric imaging device. As used herein, the phrase xe2x80x9cphotoelectric imaging devicexe2x80x9d means any device that generates image data representative of an image of an object through use of a photosensor array. Examples of photoelectric imaging devices include devices such as camcorders and digital cameras that instantaneously focus an entire image that is to be captured onto a two-dimensional photosensor array. Another example of a photoelectric imaging device is a line-focus system as described below.
Some line-focus systems image an object by sequentially focusing narrow xe2x80x9cscan linexe2x80x9d portions of the image of the object onto a linear photosensor array by sweeping a scanning head over the object. The scanning head is an imaging device or has an imaging device located therein. Examples of such devices include computer input devices such as optical scanners, which are commonly referred to simply as xe2x80x9cscannersxe2x80x9d. Other examples include facsimile machines and digital copy machines.
A line-focus system is also used in some barcode readers. Generally, in line-focus barcode readers, a narrow portion of a barcode is imaged onto a linear photosensor array. Electrical output from the photosensor array may then be analyzed to read the imaged barcode. Examples of imaging devices that are useable in conjunction with barcode readers are disclosed in U.S. Pat. No. 6,118,598 of Gardner, Jr. for METHOD AND APPARATUS FOR SETTING FOCUS IN AN IMAGING DEVICE and in U.S. patent application Ser. No. 09/290,216, of Gardner, Jr. for ALIGNMENT APPARATUS AND METHOD FOR AN IMAGING SYSTEM, which are both hereby specifically incorporated by reference for all that is disclosed therein.
Referring to FIG. 1, a schematic view of a conventional line-focus system is provided for illustrative purposes. The line-focus system is provided with a light source 308, a plurality of light beams 310, 312, 314, a plurality of reflected light beams 320, 322, 324, a lens assembly 330, a linear photosensor array 340 and a data processing system 370. A use for such a line-focus system is for reading labels, perhaps a barcode 350 located on an object, such as a media storage device 360. The distance between the lens assembly 330 and the barcode 350 may be referred to as the object distance Lo. The distance between the linear photosensor array 340 and the lens assembly 330 may be referred to as the image distance Li. In the line-focus system, light beams 310, 312, 314 are emitted from the light source 308 and are focused or directed onto the barcode 350. The light beams 310, 312, 314 reflect off of the barcode 350 as reflected light beams 320, 322, 324. Line focus systems are described in U.S. patent application Ser. No. 08/888,339 of Kershner for CATADIOPTRIC LENS FOR A SCANNING DEVICE, which is hereby specifically incorporated by reference for all that is disclosed therein.
The reflected light beams 320, 322, 324 converge at the lens assembly 330. After converging at the lens assembly 330, the reflected light beams 320, 322, 324 are focused onto the linear photosensor array 340. The linear photosensor array 340 may, for example, be a single dimension array of photoelements, wherein each photodetector element corresponds to a small area location on the barcode 350. These small area locations on the barcode 350 are commonly referred to as xe2x80x9cpicture elementsxe2x80x9d or xe2x80x9cpixels.xe2x80x9d The reflected light beams 320, 322, 324 travel from a corresponding pixel location on the barcode 350 to the linear photosensor array 340. Each photosensor pixel element in the linear photosensor array 340 (sometimes referred to simply as a xe2x80x9cpixelxe2x80x9d) produces a data signal that is representative of the light intensity that it experiences. All of the photoelement data signals are received and processed by an appropriate data processing system 370.
In imaging devices, and particularly in a line-focus type imaging device as described above, it is preferable that the reflected light beams 320, 322, 324 from the barcode 350 be accurately aligned with and focused onto the linear photosensor array 340 in order to accurately image an object. In a typical line-focus scanning device, the reflected light beams 320, 322, 324 are transmitted by one or more optical components, such as the lens assembly 330 before reaching the linear photosensor array 340. Even a slight misalignment between any of these optical components and the linear photosensor array 340 will likely result in a corresponding degradation in image quality.
Scanning devices that include light beam alignment features are fully described in U.S. Pat. No. 5,646,394 of Steinle et al. for IMAGING DEVICE WITH BEAM STEERING CAPABILITY, U.S. Pat. No. 6,147,343 of Christensen for PHOTOELECTRIC IMAGING METHOD AND APPARATUS, and U.S. patent application Ser. No. 09/813,205 of Schmidtke et al. for METHOD AND APPARTUS FOR SETTING FOCUS IN AN IMAGING DEVICE, 2001 which are all hereby specifically incorporated by reference for all that is disclosed therein.
Typically, the optical components in an imaging device are mounted within an imaging device housing. The photosensor array is typically mounted to a circuit board, which, in turn, is mounted to the imaging device housing. A lens is also typically mounted within the imaging device housing. The lens serves to focus an image of an object onto the photosensor array. In order for the image to be accurately focused onto the photosensor array, and therefore the imaging device to function properly, the focus of the lens must be located at a precise position within the housing. Additionally the distance between the object and the lens assembly should remain constant. By retaining the object distance, the overall quality of the image remains constant.
After a conventional imaging device is assembled, the image distance Li (FIG. 1) is generally adjusted once to focus an object located at the object distance Lo (FIG. 1). Typically, this is done by adjusting the distance between the lens and the photosensor array, i.e., the image distance Li (FIG. 1) of the optical system, until the proper focus is achieved. To accomplish this, imaging devices are commonly provided having a reference surface or surfaces for locating the lens relative to the photosensor array. These reference surfaces typically allow the lens to translate in only one degree of movement, i.e., in directions toward or away from the photosensor array, but prevent the lens from being displaced in other directions.
Imaging devices also typically include a bracket or some other retention device to lock the lens in place against the reference surface or surfaces after the focus of the imaging system has been set. The bracket may, for example, be secured by a screw. Accordingly, the screw may be loosened when it is desired to move the lens in order to focus the system, and then tightened to lock the lens in place when the proper focus has been achieved. This adjustment is for preliminary focusing and calibration of the system at the time of manufacturing and is typically not capable of adjustment while the system is in operation.
FIG. 2 schematically illustrates a focus setting device 400 which may be used to set the focus of an imaging device. The focus setting device 400 may generally include a fixture 410 and a moveable arm 420. The fixture 410 is adapted to securely hold a sidewall 46 of a device, as shown. A moveable arm 420 may be adapted to move in the directions indicated by the arrows 422, 424 and may include a transverse portion 426 which is adapted to engage a lens assembly 260, as shown. To set the focus of the imaging device, the sidewall 46 may be placed into the fixture 410 of the focus setting device 400, as shown in FIG. 2. The lens assembly 260 may be placed onto a lens mounting area. A lens retention member 262 may then be placed over the lens assembly 260 and tightened. The resulting focus setting is a one-time setup procedure typically performed by the manufacturer.
Disclosed herein is a method of adjusting the focus of an imaging apparatus in a media library device of the type adapted to store a plurality of media storage devices. The method may comprise providing the imaging apparatus with at least one lens, providing a movable housing and movably mounting the imaging apparatus to the movable housing. The method may further comprise providing a picker assembly movably mounted on the movable housing, contacting at least one of the media storage devices with the picker assembly and adjusting the focus of the imaging apparatus by contacting at least a portion of the imaging apparatus with the picker assembly.
Further disclosed herein is a media library device of the type adapted to store a plurality of media storage devices. The media library device may comprise a movable housing and an imaging apparatus comprising at least one lens. The imaging apparatus may be mounted to the movable housing and movable relative to the movable housing, and an assembly movably mounted to the movable housing. The media library device has at least a first operating condition and a second operating condition. In the first operating condition, the imaging apparatus is at a first position relative to the movable housing, the assembly is at a second position relative to the movable housing and at least a portion of the assembly is in contact with at least a portion of the imaging apparatus. In the second operating condition, the imaging apparatus is at a third position relative to the movable housing, the assembly is at a fourth position relative to the movable housing.
Further disclosed is a method of adjusting the focus of an imaging apparatus in a media library device of the type adapted to store a plurality of media storage devices. The method may comprise providing the imaging apparatus with at least one lens, mounting the imaging apparatus to a movable housing and moving the movable housing to a position adjacent a first one of the plurality of media storage devices, the housing being a first distance from the first one of the plurality of media storage devices. Additionally, using the imaging apparatus to form an image of at least a portion of the first one of the plurality of media storage devices. The method may further comprise moving the movable housing to a position adjacent a second one of the plurality of media storage devices, the housing being a second distance from the second one of the plurality of media storage devices. The method may further comprise adjusting the focus of the imaging system and using the imaging apparatus to form an image of at least a portion of the second one of the plurality of media storage devices
Further disclosed is an imaging system for forming images of a plurality of objects. The imaging system may comprise at least one member and at least one imaging assembly movably attached to the member. The at least one imaging assembly comprising at least one lens and at least one photosensor. Additionally, the imaging assembly comprises at least a first condition, and a second condition. In the first condition the lens is in imaging relationship with the at least a first of the plurality objects, the lens is located at a first distance from the first of the plurality objects and the imaging assembly is located at a first position relative to the member. In the second condition the lens is in imaging relationship with at least second of the plurality of objects, the lens is located at the first distance from the second of the plurality of objects and the imaging assembly is located at a second position relative to the member. Wherein the second position is different from the first position.